Out of universe of course this is because Lucas never said anything about the Jedi Order being celibate, or not allowed to love and marry.
As of AOTC, all the EU stuff featuring Jedi with girlfriends, husbands, wives, kids, etc and genetic Force dynasties had to be retconned, so they just said Luke didn't know about the rule and (if and when) he found out that it used to be a rule just changed it.
Was a reason given for him changing the rule? Was he just pulling a Henry VIII and just doing it so he could marry his main squeeze? Or did he find out about it too late and didn't want to break up the marriages of his fellow Jedi?
The question we have to ask ourselves also is... does sexual reproduction actually prepetuate Force Ability?
How come Anakin, who has great force ability, and somebody with none like Padme can have a kid with great potential (like Luke)? Maybe this is just a special case because he's the Chosen One.
Otherwise you'd think the Jedi would have a massive breeding program to make sure they always had people to train and enough staff to protect the galaxy. As it is they are overwhelmed.
Do the deliberately limit themselves because the populance fears a Jedi Order that is too powerful? Maybe they do it for political rather than spiritual reasons...
If Jedi have attachments, family, wealth, etc. they may have divided loyalty to the Republic and be unable to serve it with 100% of their being (or that is the temptation anyway), a similar reason to why some religious groups prohibit marriage for clergy or monks. Freeing themselves from attachments such as these allow them to devote their whole lives to their cause.
I mean what if you have a bunch of kids and they don't want to become Jedi? What if you get a bunch of money, when you die, where does all that money and property go? Do you take funds from the Jedi Order and the Republic and give it to your kids who don't share their parent's ideals?
The whole idea of Jedi being these child-stealers who take kids kicking and screaming from their homes (in-universe propaganda in the EU, courtesy of "HoloNet News") would be easily remedied by a selective breeding program. Have Jedi Mothers and/or Fathers pump out the force brats and you have no problem. Or clone them like the Kaminoeans do if sex is a bad thing. Heck, you could even just do them test tube if cloning is against Jedi ideals or something...
Lots of possibilities, as I see it.