Question

1 if the concordance rate of a trait in mz twins is 0.20 and the concordance rate in dz twins is 0.16, what may this mean? a there must have been an error in carrying out the study as mz twins should always have a significantly higher concordance rate. b the behaviour may have a genetic basis, but only in some people. c the behaviour is most likely genetic. d there may be no genetic link to the behaviour, the behaviour is most likely the result of environmental factors.

Explanation:

Concordance rates compare trait similarity between twin pairs. Monozygotic (MZ) twins share 100% of their genes, while dizygotic (DZ) twins share ~50%. A small difference (0.20 vs 0.16) between MZ and DZ concordance suggests genetic factors have little to no meaningful influence, as a strong genetic link would show a much larger gap between MZ and DZ rates. Option A is incorrect because small differences can occur without study error. Options B and C are not supported, as the minimal gap does not indicate a likely genetic basis.

Answer:

D. There may be no genetic link to the behaviour; the behaviour is most likely the result of environmental factors.