I have read in different places that Aramaic does not have an actual word for cousin, and brother was routinely used for close relatives. I'm sure you will disagree, but you may find these link helpful.
http://www.totustuus.com/virgin.htm
http://www.davidmacd.com/catholic/mary_perpetual_virgin.htm
http://maryimmaculate.tripod.com/marian7.html