If your mom's family members all have very dark skin and your ...

[meagbuch]

If your mom's family members all have very dark skin and your dad's family members all have very light skin, your skin color may be somewhere in between. Each parent's genes contributed in a(n) ______ fashion.
 
  dominant-recessive
  dizygotic
  additive
  nonadditive

Question 2

Why is it difficult to determine exactly how many genes are in the human genome?
 
  because the human genome project is ongoing
  because the genome is constantly changing
  because DNA mutates over time, therefore changing the appearance of
  genes
  because it is sometimes difficult to tell where one gene ends and another
  begins

[kilada]

Answer to Question 1

additive

Answer to Question 2

because it is sometimes difficult to tell where one gene ends and another
begins

[meagbuch]

YES! Correct, THANKS for helping me on my review

[chereeb]

Thanks for the timely response, appreciate it