Annamill, You aren't the first to question and there are treatise out there of "complicated" scholarship and international best seller status which set out to explain that a) Jesus and Mary Magdeline were married.
b) Had a daughter and two sons
c) This lineage is the basis of the divine rite of Kings
d) Arthurian Legends and the Holy Grail also come out of this quest. etc. etc.
Oh,did I mention the conspiracy to keep this information out of public reach? I enjoy a good intellectual tangle, but this one is CONVOLUTED & COMPLICATED. If anyone has any interest you can find it here...

http://www.geocities.com/CapitolHill/Congress/2301/bookish.html

TINKER