Science is a good thing. And I have an appreciation for it. Research is a good thing.
However, there is a big, "but" in all of this.
In the animal kingdom, survival of the fittest, drives, who gets to get who.
In the human kingdom, with it's capability of abstract thinking, and sometimes skewed thinking and emotions, we make choices, that are not always in our best interest.
That being said, why does the fat guy, marry the skinny girl? Why does the fat girl end up with the skinny guy? Whey does the ugly, short, squatty person end up with a tall hottie?
Why do some people, decide, to forgo the whole intimate relationship thing, like their job, and get a dog?
Why do some, like my boss, at 72, and need Viagra, still insist on chasing women? Good night, he's had 3 wives and numerous significant others!
They have all liked his money!
Why do 2 of the heaviest people I know, who have a son who is 17, and were told they would never conceive again, because of their weight, now have 2 little kids, at 40+? They are great parents!
Why does a girl from a reasonably good home, with a high school education, decide it's a good plan to get pregnant, and the daddy is now in jail, and there to stay for a good while. And has 4 other kids he does not support?
But she "LOVES" him.
I could go on and on with examples.
The thing is surveys, studies, and so on. No matter what you do, you will never do a total survey/study that will cover all of the human bases.
There are too many differences, in social structure, beliefs, environment and so on to ever label people!
Case in point, suicide bombers! Seriously, who does that? How do you train for that profession?