Kitten not grooming

I adopted 2 kittens (Brother & sister) when they were 6 - 7 weeks old they are now 12 - 13 weeks I have noticed however that my boy isn't grooming, although the girl is. I believe he was the runt as he has a lazy eye at times and can be very clumsy compared to his sister, who is always full of beans.

He is always climbing into the shower with me (ever since I got him) and seems to love the attention in the shower more than the water.

I had noticed that his coat is nothing like his sisters and he is never grooming. (I have seen him lick his paws(dinner time) and the side of his belly(only once)).
His fur clumps together as if it was greasy, so I decided to actually wash him when he came into the shower yesterday and he loved it (i used a very mild 2in1) he even enjoyed being rinsed under the shower (I held him close to the head (the water was luke warm- i was freezing!) at soft setting) being careful not to wet his head. Afterwards i wrapped him in a towel, holding him in my arms and rubbed gently till he was dry. What scared me though was that once I had dried him he did not lick himself afterwards (just his two front paws).

Is this just behavioral or could it be something bigger?

p.s his sister grooms his head.

Hi and welcome.

Bless his little sister for trying to help him by washing his head! lol

I would say the kittens were very young when they left momma and she just hadn't finished teaching them all they needed to know. Kittens should really stay with mum a minimum of 10 weeks but 12 is even better. It gives momma time to finish teaching them how to care for themselves and some good manners.

Its sweet he liked to shower with you and wasnt afraid of the water.
Have you tried brushing him daily?
I really dont know what to suggest. Maybe you could try taking a damp wash cloth over your finger and trying to mimic the action of momma's tongue!!
Sorry if that just sounds plain silly.

Im sure someone with much more experience of this will be along soon to advise you.

you say about the lazy eye , has this been checked out by a vet atall? , it could be that his unwell or has something wrong which is why he wont clean him self ( i hope not) or it could be like the above poster said he wasnt ready to leave his mum. i had a brother and sister come to me when they was 4 weeks old , the sister would clean the brother for him as he didnt seem intrested in doing so , there a year old now and he does it himself ( the last 4 months) lol.