Idioms

The family

it runs in the family - an ability or talent that is passed on through the generations
your own flesh and blood - a member of your family, do not forget it!
bad blood - hostility or unfriendliness between two families or family members
blood is thicker than water - family ties are stronger than any others, despite arguments.

• He has two daughters, both very athletic, just like their mother. It runs in the family.
• You should take better care of your younger sister. She is your own flesh and blood.
• There is bad blood between the two brothers. They haven't spoken to each other in two years.
• His housekeeper had looked after him for many years but he still left all his money to his only son. Blood is thicker than water, you know.

Mother

mum's the word - it's a secret, don't tell anyone
mother nature - nature and its benevolence towards human beings

• Dora doesn't know about Jim's affair with Marion, somum's the word.
• It's a nasty sprain but leave it all to mother nature and it will heal naturally.