There are plenty of fish in the sea, all but one of them is not your brother. If your still living at home your not mature enough to make a decision that will not only turn your world upside down but will have outstanding biological consequences for would be grand and great grand children. Chances are Oedipus and Electra here will get over it eventually and be able to live easier lives if they just wait it out.
Its just not worth it.
Be warned: If you go through with it and you are found out you WILL be separated.

And assuming the OP is not a troll, do either you or your brother have a sense of taste or smell? Its actually relevant.