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									A comparison of asymmetry
 between monozygotic and
dizygotic twins and siblings

   By: Lisa and Laurie DiMente
After reading “Genetic variance in the pattern of the growth
curve for height: A longitudinal analysis of male twins”, and
“A serial study of normal facial asymmetry in monozygotic
  twins”, we became interested in the asymmetry of twins,
           compared to the asymmetry of siblings.

      We were intrigued by this subject because the
        article about height said that there was more
      symmetry in monozygotic twins then any other
     sibling pair. Yet the article on facial Asymmetry
        said that asymmetry was not related to twin
 These differences in the journal articles led
 us to wonder if asymmetry in hands and
 feet of siblings could be related to zygosity.
 What we expected from this experiment
 was that twin pairs especially monozygotic
 twin would have a lower difference of
 asymmetry than normal sibling pairs.
      2            Using metric ruler take
                    measurement of fingers 1-
                    5 from tip of finger to
                    bottom crease of finger.
  1                Then take measurement
                    from tip of finger 3 to
                    measure point in diagram.
  3 4 5
                   Repeat this on both hands
                    and feet.
Measure point      Record measurements
         Equations used to figure out
          differences of asymmetry
   X= fingers of right hand and hand measurements
   Y= fingers of left hand and hand measurements
   for each finger and hand | X-Y | = Z
   Sum of all Z / 6 = S (hands)
   Do the same equation to get Sí(foot)
   [S (hands)+S (feet)] / 2= P
   P is the total asymmetry of the person
   Then find the difference between siblings by subtracting the total
    asymmetry of each person
Sibling differences (Table 1.)

 Dizygotic twins     .15
 Monozygotic twins   .0333
 Dizygotic twins     .35
 Sibling pair a      .1176
 Sibling pair b      .0917
 Sibling pair c      .025
 Sibling pair d      .1083
 Sibling differences cont. Table 1

Sibling pair e   .0000000000000004
Sibling pair f   .1417
Sibling pair g   .0667
Sibling pair h   .2667
Sibling pair i   .1167
The data presented in table 1. shows that there are no
     trends related to zygosity and asymetery.

     Though there are no trends in the results it
     must be understood that it could be due to
      an extreamly small sample size. If one
     wanted to repeat this experiment it would
       be beneficial to have a larger sample.
  From the data obtained our origional hypothesis
 must be rejected, though the results may vary if a
larger sample size was to be used. As shown from
    table 1. the smallest amount of difference in
      assymetery was found in siblying pair e

   and not in a twin pair as we hypothosised.
   As stated in ìA serial study of normal facial
      asymmetry in monozygotic twinsî our
   findings support that asymmetry could not
           be related to twin zygosity.
   Bergman, P.,Belicki, T.,Hauspie, R.C. and, Susanne, C.
    1994. Genetic Variation in the pattern of the growth curve
    for height: A longitudinal analysis of male twins. Annals
    of Human Biology, vol. 21, no.4:347-362.
   Burke, P.H. and Healy, M.J.R. 1993. A serial study of
    normal facial asymetery in monozygotic twins. Annals of
    Human Biology, vol. 20, no. 6: 527-534.
   (For information about raw data contact Laurie DiMente at
    Spring79@juno.com or Lisa DiMente at

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