He wondered which was stronger, the byakugan or the sharingan? Which blood would dominate if they were mixed together? Which genes were stronger?
The blood of one clan would end if they did mix.
It was his duty to kill his brother and restore the clan to its former glory. That was why he needed a wife, preferably a kunoichi who was strong and would help advance his line.
However, the uncertainties of mixing their blood was dangerous.
Sasuke had to rule Hinata out. But a nagging in the back of his mind told him it was probably worth it.