8 years, 3 months.

Dear Holly,
Despite me giving your brother a standing offer to teach him how to play guitar, met by him continually choosing other hobbies instead, you will apparently be my child who actually shares an interest in performing music.
It appears that you and your cousin Darla have now formed a pop duo. (An official name has yet to be determined.)
She plays the ukulele while you take care of lead vocals. You both share the responsibility of songwriting.
I am so proud, and relieved, to know that at least one of my children will carry on the music legacy in our family.
Love,
Daddy
