It really is so variable. Our Monster was off the charts for height (i.e. higher that the 100th percentile) when he was CJ's age and the paediatrician said he was perfectly normal. He is now 5.5 months old and weighs just shy of 10kgs. We also get the comments as he is often bigger than some much older kids. Our nurse said that as long as he is in proportion everything is fine.

...and he has been formula fed, not breastfed...