how can you tell if a five year old girl is bipolar like one of her relatives?

Hello and thank you for sharing your question.

You must be very careful not to mistake normal ups and downs of a child with this serious mental illness.  Misdiagnosing a child can be very harmful to their development.

A child with bipolar disorder has mood swings that are powerful and disrupt their performance in school and their ability to make friends.  These mood swings are characterized by extreme happiness followed by extreme depression.  

This is a very complex illness and I suggest you speak with a specialist about the specific symptoms you see in your child.  You can read more about the disorder in children at the link below.

http://www.nimh.nih.gov/health/publications/bipolar-disorder-in-children...

I hope this helps.

Faith