I could usually tell my Wyandotte crosses as they matured. The rose comb was the giveaway for me, as they were my only rose combed breed, but they were always a good pound or so heavier. Not so different to look at, but when you picked them up you could tell the difference. Here's a hen from the...
Twins, anyone? This is a barred Rock rooster over a SLW hen, so just sub yellow skin for your guy's white skin and it's pretty much the same. First pics were around 3-4 months.....pretty scraggly looking.
Here's around 6 months. The Wyandotte influence really kicked in and I got a...