ANSWER:
I don't think we can use "astrology" to find out if a baby will become a problem or unfaithful. One way you can find is how this person will grow up, how the parents will raise the baby, and what kind of environment he or she will grow up. Not some silly "astrology." Sorry!
Sagittarius
Virgo
Taurus
Virgo, Gemini
Leo is the sign associated with royalty. Capricorn seeks status and respect as well.
His birth sign is Pisces.
He's a Gemini, the most flexible birth sign.
The mutable signs are considered to be the most changeable: Gemini, Virgo, Sagittarius and Pisces.
Perhaps Gemini people are. They are very youthful and carefree, that's why.
No, you cannot sign a birth certificate if you are not the biological father.
You haven't explained whose birth certificate. If it's her biological child then she must sign the birth certificate. The biological parents of the child sign the birth certificate.
That's NOT easy - Scorpio is the most private birth sign.