Gestational diabetes makes sense. When my oldest was born in 1977 another woman down the hall from my wife had gestational diabetes and her son was 12.5 lb. and that kid was big.
bttt
Yeah...my mother was diabetic and I was nearly 13 lbs at birth...she weighed in at about 100! I was the biggest kid in my class all the way through the 10th grade, when everybody else started to grow.