She was curious and naive…..
Well, I gave her 2 sets of answers.
The standard answer :-
Men have what is referred to as libido…or sexual drive that is due to the natural presence of male hormone or testosterone in their bodies.
Enough or stronger dose of Testosterone makes men easily aroused or stimulated visually..as opposed to women who are stimulated in more subtle and more complex ways.
So, nature designed males to become stimulated and ready for sex with any visual queue that a female was ready for fertilization.
One of the adaptations that human females made was to develop fatty tissue in their breasts so that they look like they are lactating all the time, a sign of fertility.
So it's not so much that men see a woman's nipples that turns them on, but that they see the shape of the female breast with the nipple that gives them the instinct to become aroused.
Females are the only ones that have developed this ability to mimic their capacity for fertility visually.
So, males have just been following along and changing with them in order to keep our species alive.
Then I gave my 2nd answer to that same question:
Picture this, God created Adam - the first man on earth about 6,000 years ago.
Adam was the only human being on earth… and he felt lonely…
And God created woman…
Her name was Eve.
Both are naked, of course…
So, If Adam cannot get a HARD ON when he see Eve, then how come our earth population skyrocket to 6.7 billion now???
Satisfied….she asked me again…
Why some men become gays and some women become lesbian????
I ran away…