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] .
Even though babies can be propped up in a sitting position with support from the day they are born, they cannot start sitting up independently on their own until they have gained head control. After learning when do babies sit up, here is how the sitting develops: