In the Gita, Lord Krishna tells us He is born from time to time to protect goodness and destroy evil. He says:
You and I have passed through many births.
I know them all but you do not remember.
I am born from time to time
whenever the good need my protection.
I am born to destroy the bad and help the good.
My birth is divine and those who understand
this become part of Me
and do not have to be born again.
Gita: 4:5; 6; 7
Human beings envision God in a form like ours. Thus we say that He created us like Him or now some of us consider perhaps like Her. At the same time we cannot imagine the Lord being conceived and born in the same fashion as we were.
In my view, the fact that so many of us not only imagine but also believe in miraculous birth validate our notion and make it true. The real question is what does truth mean?
For some answers, see The Gita, A New Translation of Hindu Sacred Scripture, and On Hinduism by Irina Gajjar.