Mendilian Genetics, or, Why I Can't Curl My Tongue

For the past few days in Biology we have been investigating genetic traits. These traits are determined by alleles. You receive one allele from each of your parents. These alleles can carry the genetic code for a dominant or recessive gene. If you receive two dominant alleles or one dominant and one recessive allele, you will express the dominant trait. If you receive two recessive alleles you will express the recessive trait. I tested myself and a variety of my family members for four different traits. These traits were: attached ear lobes, widow's peak, hitchhiker's (bent) thumb, and ability to curl your tongue. My findings are below.

From this chart I was able to create the following three pedigrees:

Pedigree for Attached Earlobes. 

Pedigree for Widow's Peak

Pedigree for Tongue rolling

I was quite surprised that only one member of my family had unattached earlobes, none of my family had widow's peaks, and that neither my cousin, my brother, nor myself was able to roll our tongues while our parents could. I found this odd because unattached earlobes are dominant, widows peaks are dominant, and tongue rollers are dominant. I was unable to create several pedigrees because my grandparents could have been AA and Aa or Aa and Aa. There were several such situations, in which it was impossible to find a result.