We may eventually find that homosexuality is a birth defect also caused by advanced maternal age. Excerpt:
http://www.scientificamerican.com/article/autism-maternal-age/
The elephant in the corner is that the definition of autism changed right about the same time there was a spike in autism cases. If you provide a more inclusive definition, of course you will have more cases. This is hardly rocket science.
I don’t know what people expect as they put off child-bearing for longer & longer periods; the “zero-birthrate” advocates don’t want it broadcast, but I think women have a smaller window to breed safely than they would want them to believe. As a parent, I just couldn’t imagine doing midnight feedings at 45 (never mind the health risks); children set you back financially, but it is a basic choice young people have to make while the opportunity is there.
If a person starts a certain sexual activity early and continues it into adulthood there's a pretty good chance they'll stay that way.
It is common knowledge: As women get older, pregnancy becomes a riskier enterprise. Advanced maternal age is linked to a number of developmental disorders in children, such as Downs syndrome. Now, a study has confirmed that older mothers are more likely to give birth to a child with autism, too.”
A friend of mine who had her first and only child at 42 was concerned about birth defects. She said she was told that as one ages the eggs get stickier. Due to stickiness, it is easier for extra chromosomes to attach to the egg causing birth defects. Young eggs are slick and things do not attach.
She has a lovely grown daughter now but defects are always likely when the mother is older.
Related to that, I have also read studies that say that the more male pregnancies a woman has had, the more likely the next male pregnancy will be a homosexual. Obviously there would then be an age correlation. But perhaps the age correlation is an artifact of the number of male pregnancies.
I’m not arguing that age is not a factor. I’m just presenting another possibility.