Without question, we are products of both our biology (or nature) and our environments (or nurture). There is no way that we are only one or the other.
Let us think, for example, about our physiques. Of course, much of this is determined by nature. A person may be inclined to get fat easily, for example. However, this does not mean they necessarily will get fat and it does not determine exactly how fat they will get. A person who grows up in a family that eats unhealthily will surely get fatter than a person who is also disposed to get fat, but who grows up in a family that eats healthily.
The same thing can happen with our personalities. Some people may be born with relatively short tempers. However, a person who is raised in a family that tries hard to get them to rein in the temper will be much less volatile than a person raised in a family in which it is seen as acceptable to get very emotional.
Thus, it is clear that both biology and environment are very important in making us who we are.