Thanks for the summary, Agnostic. I look forward to reading my copy of No Two Alike when it comes in the mail.

So this a warning to all those planning on having their cats cloned? It won't be the same old Fluffy.

Very interesting theories about germs/microbes & how they could be affecting us.


We know that identical twins don't look exactly alike, but how alike are their brains in morphology i wonder?


All this talk about *No Two Alike* reminds me of the *Supervenience Theory of Mind/Mental Properties*.

Is every mental(personality, IQ)difference also a physical/brain difference?

How would you/she account for the well-known phenomenon of daughters of alcoholics marrying alcoholics? This (and similar behavior) has very a profound influence on personality - and it would seem to be a result of "shared environment".

How would you/she account for the well-known phenomenon of daughters of alcoholics marrying alcoholics? This (and similar behavior) has very a profound influence on personality - and it would seem to be a result of "shared environment".

no, you assume it has a profound effect. it could be that there are common impulsivity and poor decision making skills common components to both alcoholism and choosing to pair up wit alcoholics. at least that's what i'd think she'd say, you can't tease apart the causes of the correlations so easily....

it could be that there are common impulsivity and poor decision making skills common components to both alcoholism and choosing to pair up wit alcoholics. at least that's what i'd think she'd say, you can't tease apart the causes of the correlations so easily....

It would seem easy to test, just look at adoptees. But the trend to marry someone who reminds you of your opposite-gender parent is general - not just for children of alcoholics.

Can I propose a survey of GNXP readers? For those of you who are married or in long-term relationships: Does your partner remind you of your opposite-gender parent?

My answer: Yes.

(It would also be interesting to know if the answers differ for marriage and long-term relationships.)

Married 30 years. My father was more like my grandfather.

I would say that I tended to seek men who were of the same age or slightly younger then I, never attracted to older males. Maybe it was to prevent comparisons.

I wouldn't say that my husband resembles my father, maybe in interest in politics and a bit of humor; but, again, this is also my interest.

Things aren't so simple.

It's possible that people who have longstanding relationship problems with their parents are more likely to seek out partners that resemble their parents, especially in those pathological characteristics, in a subconscious desire to finally work out those problems. (You can substitute "subconscious" for something more straightforward, but more wordy.) I read a whole book with this thesis by some psychologist.

Alternatively, one's relationships skills might have been developed so much to cope with the specific problems one's parents had, that one simply feels more comfortable in relationships where one re-enacts those dynamics than in a more healthy, but unfamiliar kind of relationship.

I'm not sure a more technical explanation would be helpful.

(I'm not married, so I can't say whether it would apply to me. I tend to be attracted to women who physical resemble my mother facially, but not to those who share many of her personal traits.)

Married 15 years, and she ain't nothing like my mother. I seem to have spent my girl-chasing and mate-seeking life running away (in a variety of ways) from my mom, who was a benign and lovely person in many ways, but also very rigid (and probably more than a bit Aspergery). I was looking for something more ... acommodating. First I chased a lot of earthy, juicy, soulful types: Jews, Italians. Settled in finally with a Lisa Kudrow type: an arty, talented space cadet. The only similarity to my mom shared by most of these gals is that "culture" was important to them. My mom didn't know much about culture or have much of a taste for art. But something about the idea of it meant a lot to her. (I think it was mostly the social, class aspect.) So I guess her presence in my history steered my tastes to that extent. But as a dater/mate-seeker, I stayed away from her general (over-organized, quietly-bossy) type almost completely.

Agnostic, thanks for a very interesting post.

David Boxenhorn: “How would you/she account for the well-known phenomenon of daughters of alcoholics marrying alcoholics? This (and similar behavior) has very a profound influence on personality - and it would seem to be a result of "shared environment".”

Relative dependence on environment, genetics, and noise depends on the specific population studied. If the “shared environment” doesn’t meet minimal standards for nutrition, safety, and stimulation, then the environmental contribution will be large. (A starving child, a physically abused child, etc.) (Yeah, I know this is obvious but sometimes the obvious needs restating.)

Perhaps the populations studied did not include a significant number of environmentally disadvantaged subjects.

Or perhaps the personality and IQ traits measured in the studies did not reflect the alcoholic’s “profound influence on personality”. (Some fish escape from the net.)

Interestingly, I just listened to a chemistry lecture on bacterial chemotaxis. It was discovered here at Cal that certain individual bacteria persistently move in the "wrong" direction or have difficulty orienting themselves along a chemical gradient, although they are genetically identical to those that have no problem following the gradient. The cause in this case was randomly increased or decreased expression of proteins of which there are few (1-15) copies per cell.

[Is every mental(personality, IQ)difference also a physical/brain difference?]

What in gods name takes place outside of physics?

"What in gods name takes place outside of physics?"

All kinds of phenomena according to the spiritual.

Well, nothing, according to hard physicalists, materialists, monists, etc, if i am not misrepresenting their views.

Of course, philosophy aside, it seems common sense that nothing is/can be outside physics.

Supervenience theory seems reasonable.

A sufficiently advanced physics will address vibrations in the aether...

Re: daughters of alcoholics marrying alcoholics, the Heath et al chapter in Behavioral Genetics in the Postgenomic Era shows that shared environment accounts for 5% or less of the variance in alcoholism, using twin or adoption studies. So it is probably what Razib pointed out: the girl's dad preferred risky ruinous activities, the girl inherited (some of) the relevant alleles, and boom, she prefers risky ruinous activities.

Any study would have to control for the drinking habits of the daughters.

Some consider alcoholism to be inherited; if that's true the daughter will probably like to take more than a drink or two herself. Since boozers like to hang around with other boozers, she would be less likely than women to date teatotalers or even social drinkers.

less likely than other women

I like Fly's answer.

David Boxenhorn,

I've dated women of all different types physically, but am often attracted to women who are more like my mother intellectually or emotionally - that would be intelligent - more math than verbal - aloof and unemotional.

In one word, personalities are the result of non-linear dynamics. Tiny, random differences (whether on a social or molecular level) between "identical" twins become cristallization points for the development of different individualities. Both genetic and cultural determinism fail to take this non-linearity into account. I don't know whether Harris' account of how this individuation happens holds water but the basic idea seems obvious to me. Almost banal for anybody who is familiar with the science of non-linear dynamics at all. What I find surprising is that this theory claims to be novel.

The MZ DZ concordance rates (MZ=59, DZ= 10) for leprosy are an error in the table... 62 MZ pairs with 37 concordant = .59+ , but the table incorrectly calculates the DZ concordance rate. 40 DZ pairs, 8 concordant SB 20% concordance....