The Japanese word for family is kazoku (家族). Just like in English, there are different ways you can refer to your parents in Japanese. These words also change depending on if you are talking about your own parent or someone else's.
Okaasan and otousan have the honorable letter O in front of them. I can be removed when talking about your own family members.
(This is my) dad = chichi desu (父です)
He is the one that is (my) dad = kare ga otousan desu
Other words used on parents are mama (ママ) and papa (パパ). This are especially used by children or from parents to their children.
When Japanese parents are around their children or grandchildren they often refer to each other as otousan or okaasan and ojiisan or obaasan, instead of using their names.
The polite suffix san (さん) can be removed and converted into another suffix to change the politeness level.
(How is your) grandmother? = obaasama wa? (おばあさまは？)
The words for aunt and uncle in Japanese can also mean a middle aged man or women. These words are also similar to Grandma and Grandpa, but the sounds are shorter. Make sure you pronounce both these words the correct length and not get them mixed up.
In Japanese there are different words for your siblings depending on their age in relation to you. The words Oniisan and Oneesan can also be used on someone who is not a relative, but a close friend. You use these words if one of your friends has a special relationship with your or bond and you feel like they are your older brother or sister.
(I) have children = kodomo wa imasu (子どもはいます)