Subject: Why can't the DNA of two males or two females be combined to produce a baby

With all of the current developments in genetic engineering, etc, why, 
theoretically, couldn't scientists combine the DNA of two same-sex parents to 
form an embryo, instead of the normal male/female combo?  (ie. taking an egg 
from one female and inserting the DNA material of their "partner" into a sperm 
that would fertilize the egg...) With two males, this could produce a YY gene--
what would this be like? 
I know this may seem like a stupid question, but I just wanted to know exactly 
why it would NOT work.  I'm a college freshman, pre-med, full of curiosities! :)

Re: Why can't the DNA of two males or two females be combined to produce a baby