I am no professional in any field. I just rely on my past life experiences/intuition all gained via appropriate intervention and resultant awareness - if you get my drift?
BUT, coming from a family of 8 children, 7 of which were girls and my mother had previously lost 2 sons very soon after birth due to common diseases way back then. So my brother was her only surviving son. I kinda of see what you may be questioning.
My father always contended that my mother loved her son/my brother, far more than any of her daughters. Was 100% a bone of contention throughout my entire formative life between them. It was extremely sad to witness too as, unfortunately, it made for much unnecessary, unpleasant interaction between my father and his only son.
From what I understand, Sherie P had a son during her teens before her relationship with Mick - ok, no problem and no judgement. Unfortunately Sherrie's first son has learning disabilities as we are lead to believe, forgive me, not sure what the current PC term is for that is these days.
Therefore, when MP came along, possibly both mum and dad were just so relieved that their new born didn't have the same learning difficulties. Wouldn't any parent?
So, yes
@KyBourbon, perhaps MP's parents maybe did treat their first born differently possibly, purely through relief, perhaps?
BUT, they weren't rich and therefore wouldn't have been able to lavish untold privileges on MP alone outside of what they could afford for the entire family, or wish to give MP, e.g. piano lessons etc - which he covered in one of his vlogs a couple of years ago.
As per my personal experience, any parent would wish to give their children whatever they can afford to help them within reason and their budget - it's a given. Isn't it?