Snape/Voldemort similarities

[ginny343]

No: HPFGUIDX 142145

If this has been discussed, I hope someone can give me a message 
number so I can go back and read it.

In GOF Barty Crouch, Jr. talks about how he and Voldemort are alike, 
mostly based on parentage.  Snape is also very like Voldemort in this 
way.  He is the son of a witch and a muggle.  A witch, like 
Voldemort's mother, who was not very attractive.  And from the memory 
we see in OoP, he probably did not have very good feelings about his 
father.  I wonder what became of Snape's parents?  Barty Crouch Jr. 
seemed to feel a bond with his master because of these 
similarities . . . I wonder if Snape also has his bond.  Or uses it to 
gain Voldemort's trust?  

I wonder why JKR wrote these characters with similar family history?

Ginny