Ethnic Jewish blood lines have been fairly well preserved throughout the 2k years since Christ. Such people have a tendancy to marry only their own kind, even cousins. The ethnic jews and palestinians I know pretty much all practice this. I think its pretty safe to say that Jesus looked pretty much like the average ethnic jew or palestinian does today. In all honesty it really doesnt matter much how dark or light his skin was. We know he was born an ethnic jew, that should speak for itself.