why do we do sex?

Answer 1

It depends on the individual, but I think there are probably just two reasons.
Firstly, it's just for fun. A kind of desire people urge for and want to experience the so-called "excitement" of it.
Secondly, it is a way of expressing your love to your partner. We have two kinds of love. Mentally and physically. Normally, people talk about the mental love, which is done emotionally. Physically is different. It can be a sign of "re-uniting two souls together to form one", by joining two bodies to become one during the process.
It depends on you now. Which one you choose.
Well, I'm surprised you asked this question, and people seem to understand this very well nowadays. Anyway, I hope you do understand it now.

Answer 2

Because it makes babies. We've circumvented mother nature a bit by inventing birth control--although half of babies born in the US are still the product of unplanned pregnancies. But if you don't ever have sex you won't reproduce, so your genes give you a sex drive and make you more attracted to people who are more likely to have good genetic material to mix yours with (young, healthy, symmetrical, smart, talented, etc).

That's part of why the genetic component of homosexuality is under such scrutiny. Twin studies have pretty much established that at least some part of homosexuality is heritable, but it's a gene that should self-select out of the population (for the same reason that infertility isn't inherited). Instead, it expresses itself in somewhere between 5 and 10% of the male population and 2 and 5% of the female population. It's a big mystery.

Answer 3

1. feels good.
2. carries on the species.
3. carries on the traits that ultimately leave your legacy to the world.
4. feels really good.

Answer 4

My best guess is your either a Virgin or you're not very good in the sack by the sounds of your question.