How do you make a muggle?

[mt3t3l1]

No: HPFGUIDX 70599

I've been discussing some of these issues in another forum. Here are 
some of my observtions so far:

1. The definition of Squib, found in CS Chapter Nine (Ron talking to 
Harry): "A Squib is someone who is born into a wizarding family but 
hasn't got any magic powers."

2. The fact that a witch and wizard can give birth to a Muggle, found 
in SS Chapter Seven: "Well, my gran brought me up and she's a witch," 
said Neville, "but the family thought I was all-Muggle for ages." 
Remember, Neville's parents were both aurors, so we're definitely 
talking about a wizard father and a witch mother. According to #1, 
Neville could have said, "the family thought I was a Squib for ages." 
Instead he chooses to use Muggle, so apparently a Squib can also be 
called a Muggle.

3. The fact that Squibs like Mrs. Figg are not registered by the 
Ministry of Magic (OOP, Chapter Eight).

In light of all this, it seems possible to me that either or both of 
Lily and Petunia's parents was a Squib. If they were, Lily could 
still canonically be referred to as "Muggle-born." It would explain 
why Mr. and Mrs. Evans "were proud of having a witch in the family." 
It could also explain why Petunia was so put off by Lily's magical 
abilities, while simultaneously being aware of obscure aspects of the 
Wizarding World like Dementors.