Nature
The coding of genes in each cell in us humans determine the different traits that we have, more dominantly on the physical attributes like eye color, hair color, ear size, height, and other traits. However, it is still not known whether the more abstract attributes like personality, intelligence, sexual orientation, likes and dislikes are gene-coded in our DNA, too.
One of the hottest issues against nature theory is that there may be an existing "gay gene", which explains that gays are actually born that way. Another issue is that the criminal acts, tendency to divorce and aggressive behavior causing abuse can be justified by the "behavioral genes" once the researchers have proven their existence.
On the other hand, the behavioral genes are somewhat proven to exist when we take a look at fraternal twins. When fraternal twins are reared apart, they show the same similarities in behavior and response as if they have been reared together.