Grandparents
Father's Side
そふ 祖父 Grandfather
そぼ 祖母 Grandmother
Mother's Side
そふ 祖父 Grandfather
そぼ 祖母 Grandmother
Parents
ちち Father
はは Mother
Siblings & Me
あに Older Brother
あね Older Sister
わたし ぼく 私・僕 Me
おとうと Younger Brother
いもうと Younger Sister

私 (わたし) vs 僕 (ぼく): Both mean "I". 私 is neutral and can be used by anyone in any setting. 僕 is more casual and traditionally used by male speakers — you'll hear it in relaxed conversation, less so in formal contexts.