Thats no different than any adoption . .
But the more likely case is
Unknown sperm donor
Two women in a committed relationship
Thats TWO people and is just the same as any hetero couple that seek fertility help.
But the more likely case is
Unknown sperm donor
Two women in a committed relationship
Thats TWO people and is just the same as any hetero couple that seek fertility help.
So there is a difference between the two.

Everyone makes a choice whether or not to act on their desires. Now if your question were when did I first have these desires for women, we could start from there. 
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