Parents – Go Ryoushin (ごりょうしん)
Father – Otousan / Chichi (おとうさん・ちち)
Mother – Okaasan / Haha (おかあさん・はは)
Brothers – Kyoudai (きょうだい)
Sisters – Shimai (しまい)
Elder Brother – Oniisan / Ani (おにいさん・あに)
Younger Brother – Otoutosan / Otouto (おとうとさん・おとうと)
Elder Sister – Oneesan / Ane (おねえさん・あね)
Younger Sister – Imoutosan / Imouto (いもうとさん・おもうと)
Children – Kodomo (こども)
Husband – Dannasan / Shujin (だんなさん・しゅじん)
Wife – Okusan / Tsuma (おくさん・つま)
Son – Musuko (むすこ)
Daughter – Musume (むすめ)

You may have notice that 2 different words are representing the same meaning. They are used in different way. Here’s how :
Q : What is your father’s name? – Anata no Otousan no o namae wa?
「あなた の おとうさん の お なまえ は?」
A : My father’s name is John – Watashi no Chichi no namae wa Jon desu
「わたし の ちち の なまえ は ジョン です」

Q : How old is your mother? – Anata no Okaasan wa o ikutsu desu ka?
「あなた の おかあさん は お いくつ です か?」
A : My mother is 48 years old – Watashi no Haha wa 48 sai desu
「わたし の はは は 48 さい です」
Meaning : Namae (Name), Ikutsu (how old – age), Sai (years old – age)
When you are talking about other people’s father, you have to use “Otousan”. For own father, use “Chichi”. Same goes to Mother, Elder / Younger Brother / Sister.

You may also notice the “O” (o namae & o ikutsu). By adding “O” is to show your respect to the person you are talking to (like your boss, customer, etc)