Copulins are short-chain fatty acids that are produced by the human female vagina, as well as the vaginas of other related primates. Copulins are pheromones that have been experimentally proven to somewhat increase the sexual attraction of males to the females that smell of them. The copulins are less effective than the steroid pheromones though.

Acetic acid (COOHCH3) is technically not a copulin, but it is often falsely believed to be one by people in the general populace. There are 6 different copulin chemicals, which are:
1. propanoic acid aka propionic acid: COOHCH2CH3
2. butanoic acid aka butyric acid: COOH(CH)2CH3
3. 2-methylpropanoic acid aka isobutyric acid: COOHCH2(CH2)CH3
4. pentanoic acid aka valeric acid: COOH(CH2)3CH3
5. 3-methylbutanoic acid aka isovaleric acid: COOHCH2CH2(CH3)CH3
6. hexanoic acid aka caproic acid: COOH(CH2)4CH3

The copulin chemicals smell bad and have been shown to damage mucous membranes when their concentration in the air is high, or when they are applied directly to mucous membranes in a liquid solution. Specificly, the copulins smell rancid, sweaty, dairy, and/or goat-like. In fact, the latin word 'caper', from which caproic acid was named, means 'goat'. Butanoic acid, unlike the other copulins, smells somewhat fruity.

That means that the copulins are clearly not the chemical(s) of the naturally-occurring human female attractant scent.