Thankyou Neuromuscular for all your helpful replies. I'm not sold on the idea that it is 100% hereditary myself i was just thinking perhaps some of it could be. The thing is my dad is the big stress head who gets angry/anxious/stressed very easily and yet his muscles are fine. While my mum isn't 100% laidback, she is in comparision. She may get a bit anxious/stressed now and again but she doesn't get angry. So it baffles me that her muscles are by far worse than dad's. Perhaps we have different places where we store tension? I know these can be pretty hard questions and i don't expect people to have the answers. Comments on peoples views or experiences would be interesting.

Again on the nature v nurture, i have found my muscles to be basically the same throughout various different occupations (nursery worker, warehouse labourer, gym instructor, student, kitchenhand). And my sister, who lives in another country, is a school teacher and used to do kayaking (as opposed to my cycling) has similar complaints. I think that possibly removes some of the nurture factor