I don't think that there are certain mannerisms for each gender. Both genders could have the same mannerisms as biting their names or whistling when they're nervous. It depends more on the person than the gender.
Some boys are just attracted to other boys. It's nothing wrong with them it's just a different way them you or I may be. It doesn't make them in any way bad people.
Because males carry both an X and a Y chromosone in his genes. If a Y chromosone inside one sperm fertilised an egg, then that child would be a boy, as the Y chromosone produces a male offspring. If...