Awwww
. It may sound very strange, but perhaps you did get sick, just because you needed the attention. And perhaps the invisibility was a good thing as well - it must be awful to be the center of all the battles between father and mother.
My mom was actually born when noone expected her mom to have another child. The pram was already delivered to the junk yard, and the same held for quite a bit of baby stuff. It all had to be bought again.
I was born the day after the 2-year anniversary of my parent's marriage. The day before my dad took my mom to a fancy restaurant. Needless to say, that my mom ended up throwing all the food up, in labour. I was due a few days later.