Final answer:
The probability of a child inheriting a normal hairline, attached earlobes, and webbed toes from two heterozygous parents is 9/64 or approximately 14.06%, considering the independent assortment of alleles and the 3:1 phenotypic ratio of each trait.
Step-by-step explanation:
Assuming both parents are heterozygous for the three traits mentioned (normal hairline, unattached earlobes, and normal toes), we can determine the chance of their child inheriting specific traits using a Punnett square. However, to simplify calculations, we will analyze each trait separately, as the question primarily asks for a specific combination of traits. For normal hairline (let's say 'H' is dominant for normal hairline, and 'h' is for widow's peak), the ratio of inheriting a normal hairline is 3:1 for a heterozygous cross (HH, Hh, Hh, hh).
For earlobes, since free-hanging earlobes (F) is dominant, and attached earlobes (f) is recessive, the ratio also follows a 3:1 pattern in a heterozygous cross. However, the question asks for the less common attached earlobes, which occur in 1 out of 4 offspring statistically (FF, Ff, Ff, ff).
Assuming 'T' is dominant for normal toes and 't' is for webbed toes, the same 3:1 distribution applies. Therefore, the chance of inheriting normal toes in a single trait cross is 75%, but the question asks for the recessive trait of webbed toes, which occurs 25% of the time.
To find the chance of inheriting all three traits mentioned (normal hairline, attached earlobes, and webbed toes), we must consider the independent assortment of alleles for each of these traits and multiply the chances of each individual occurrence. The chance of a child having a normal hairline, attached earlobes, and webbed toes is (3/4) for a normal hairline, (1/4) for attached earlobes, and (1/4) for webbed toes. So, the probability is (3/4) × (1/4) × (1/4), yielding a 9/64 or approximately 14.06% chance.