Grandma is a witch.
Magic skipped a generation with her Squib daughter, but George was a wizard. His medicine was a potion, created as a combination of involuntary magic and a strange mood.
http://tvtropes.org/pmwiki/pmwiki.php/WMG/GeorgesMarvellousMedicine
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Magic skipped a generation with her Squib daughter, but George was a wizard. His medicine was a potion, created as a combination of involuntary magic and a strange mood.