I don't know if it is ethical to ask a question like that, but I would like to know every simple physical trait that I can observe on me, my parents and my siblings which are regulated by a single or really low number of genes. I don't want any disease-related traits, just simple traits that could illustrate genetic relatedness.

Already done search
During my research I've found about:

  • Hair on the second phalanx which is controlled by a single gene and absence of hair being recessive. (Recessive means you need two copies of the allele to have the trait absence of hair!) So if both parents have the trait absence of hair (on second phalanx), every child must have it as well.
  • Merged ear lob is also a recessive trait.

These are some for which I am not sure of the underlying genetics.

  • Hair in V on the forehead
  • Presence of dimples
  • Able to make a U with tongue
  • Able to detect Phenylthiocarbamide (PTC)

Don't hesitate to answer with references

EDIT: This site is saying that both hair in second phalanx and merged ear lobs are not as simple as they seemed...

Question: What trait can I use to illustrate genetics?

  • $\begingroup$ What do you mean by "physical trait"? I assumed you meant something visible, but "Able to detect Phenylthiocarbamide" doesn't come under that. Put another way, what would a "non-physical" trait be? $\endgroup$
    – arboviral
    Commented Mar 9, 2018 at 11:55
  • 1
    $\begingroup$ Well, it would mean something easy to assess for a classroom (and no lab studies), To be honest I wasn't thinking about PTC when first writing the question. for example blood type is not easy to assess without a lab. I agree physical is not the best way to say that $\endgroup$
    – Untitpoi
    Commented Mar 9, 2018 at 22:51

1 Answer 1


Here are the answers for your four questions:

Hope it helps!

*See comments

  • $\begingroup$ So i shouldn't use Curling tongue to illustrate genetic trait :-(. $\endgroup$
    – Untitpoi
    Commented Feb 27, 2018 at 13:53
  • $\begingroup$ @Untitpoi probably not. There's even some discussion about the phenylthiocarbamide gene being more complex than a simple dominance. $\endgroup$
    – rotaredom
    Commented Feb 27, 2018 at 13:59
  • $\begingroup$ I found that Dimples is irregular as it can change along the life (like curling tongue) learn.genetics.utah.edu/content/basics/observable $\endgroup$
    – Untitpoi
    Commented Feb 27, 2018 at 14:04
  • $\begingroup$ Hmm, interesting, I wasn't aware of that one. I'll edit to reflect that. $\endgroup$
    – rotaredom
    Commented Feb 27, 2018 at 14:08
  • 1
    $\begingroup$ Well these was more complicated than i have expected, almost no trait are really controlled by one gene... the only one i have found with no doubt on it is dry earwax udel.edu/~mcdonald/mythearwax.html $\endgroup$
    – Untitpoi
    Commented Feb 27, 2018 at 14:26

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