Why am I being charged a blended tax rate with my parents. They claim me on their return, but I didn't have any unearned income.

[taxlady28]

Blended tax rate is an accounting term.  They added it to TurboTax this year and caused a lot of confusion.
It really is not the tax rate that you or your parents are paying.  It is just information and really means nothing to most TurboTax users.  

Here is a definition:

A blended tax rate is a net percentage of your total tax compared to your total income. It takes into account the different tax rates you are taxed at for different income levels. The blended tax rate is arrived at by considering various factors such as earned income, unearned income, stocks, bonds, interest, dividends, and self-employment. The blended tax rate is not used to calculate taxes, but is simply informational. The blended tax rate may be used to recalculate tax due in certain situations.

[xmasbaby0]

Not sure why you think your parents' income has anything to do with the tax rate you are subject to.   If you are a dependent, you can still file your own tax return, but you must say on your own return that you can be claimed by someone else.  You do not enter "who" can claim you.   There is nothing about your parents' tax rate that is being used to calculate the tax on the income you received.

CAN I FILE A RETURN IF I AM A DEPENDENT?

If you can be claimed as a dependent on your parents’ return, you can still file your own return so that you can receive a refund of taxes withheld.  (You will not get back anything for Social Security or Medicare withheld.) Be sure that on your own return you say that you can be claimed as a dependent on someone else’s return.

https://ttlc.intuit.com/community/children-dependents/help/do-i-need-to-file-my-own-taxes-if-i-m-a-d...