Below is a copy of the family tree involved in Shia Islam, starting with Mohammed's grandfather (Abdul Mutallib), then Mohammed's uncle (Abu Talib), followed by Mohammed's cousin (Ali—seen in Shia as the first Mahdi - the rightly guided one) who married Mohammed's daughter (Fatema) and had two sons Hasan (2nd Mahdi) and Husain (3rd Mahdi). And so on.

From http://upload.wikimedia.org/wikipedia/en/f/f0/Tree_shia_islam_n3_.pdf