My grand daughters head is an odd shape down one side and into the back of her head should i be worried?

she only lays on the opposite side to the miss shape, we have been told that she has a week muscle in her neck and needs physio but the appointment is for january, her dad, my son was born with hydrocephalus and i am worried that it is hereditary. she is 8 weeks old and we are very worried, any advice would be appreciated