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[–]MarkTwainiac 4 insightful - 1 fun4 insightful - 0 fun5 insightful - 1 fun -  (0 children)

Great post! Thank you. One quibble, about where you said

Healthy boys receive a spike of testosterone during infancy (0-6 months) that develops their genitalia. Then there's no major difference until puberty.

The spike of testosterone that males go through in the first six months of life - usually lasting for 5 months from the end of the first month through the end of the sixth - does more than develop the male genitalia. It seems to set up males to develop many physical features that will give them advantages over females in strength, size etc that later will have bearing on sports. Such as larger hearts and lungs, more muscle mass, faster twitch fibers, greater levels of blood oxygenation, etc.

Growth rates and size/weight charts for infants and young children differ depending on whether the child is male or female, largely as a result of the male "mini puberty" that occurs in the first six months of life. It's not just the male genitals that are affected.