Why is incest wrong. Why is it such a taboo thing?

Sure they can. Just don't make any babies.

Now let's say that the mother and son fuck. What if they don't want a baby. Is it alright then?

you asked why it was wrong and genetically speaking it creates disastrous affects. This is why the human mind has naturally grown accustomed to thinking the scent of those who share common genetic characteristics is off putting.it is wrong Because your mind understands that sex is for making babies and you along with most of humanity have abstracted it away from that allowing homosexuality, bestiality, incest, and any other sexual stimuation with no genetic benefit. In other words, It is wrong, Because it is wrong, because it is wrong. hope that clears things up, op.

So everybody who wants to fuck has to have kids?

no but you only want to fuck because your mind is trolling you into wanting to have kids through immediate gratification.

Is birth control a valid option?

birth control messes up a woman's hormones making her body think it is pregnant so it doesnt release eggs for fertilization. This allows the mind to change it's scent attraction and it actually makes women crave to be near men that are genetically similar to her for family protection during the period of time she is "pregnant". It messes up our bodies natural inclination to evolve.

In conclusion: Anything is a valid option for retards like most of humanity.

...

It's an evolutionary mental defense so that human beings don't make fucked up offspring.

On a rational level, there is nothing wrong with it unless you plan on having children.

If something doesn't hurt anyone, it's not wrong. Still, I'm not gonna fuck my sister.

Just use protection and it's fine by me
your business is your business