Secondly, they aren't white.. While some double merle dogs are almost pure white, they can go the complete range all the way up to a dog that you would think is a just a normal merle (most fall somewhere in the middle).
In between five and six months, your baby usually starts to sit up with your help, holding his head in an upright position, keeping the back straight. He may even be able to sit for a second or so without taking any assistance from you, before toppling down after a while [1] .
Average time for a little one to begin sitting up on their own is 6-8 months. However, every child is unique. If your child was born prematurely there might be a set-back. In most cases this set-back is in accordance with the amount of time he/she was born early.