In the Shafi'i madhhab, considerations of lineage are valid reason to refuse a marriage proposal (i.e. Hasanis and Husaynis preserving the Ahlul bayt lineage). Here is a good, brief advice on choosing a spouse: http://www.youtube.com/watch?v=q9naaQ-p--g Language and culture is important consideration because it can lead to misunderstanding and divorce. Allahu Alaam.