Opinions might not be genetic, but someone raised by liberals/conservatives is more likely to take on their parents opinions. There are some people worried about an Idiocracy like scenario where right wing people have way more kids than left wing people leading to a large shift in the political landscape, Not saying that its likely to happen though since birth rates seem to be lowering across the board.

They kind of are, though…
Everything about your personality is just as much nature as nurture, and that includes political opinions.