Although we know that siblings are different in many ways, they also vary in phenotype and skin color. Very rarely do studies examine sibling differences in skin color.
Yup, It is very possible and in-fact occurs quite frequently amoung people of biracial/mixed race backgrounds. Ex: two of my three siblings are a tad darker or have a bit more “tan" hue in their complexion than myself and my sister.
The short answer is, yes! A couple can have a baby with a skin color that isn't between their own. The long answer, though, is much more interesting. The long answer has to do with the parts of your DNA that give specific instructions for one small part of you.
But brothers and sisters don't look exactly alike because everyone (including parents) actually has two copies of most of their genes. And these copies can be different. Parents pass one of their two copies of each of their genes to their kids. Which copy a child gets is totally random.
Summary: The quantity and quality of melanin are regulating by the expression of genes. The enzyme tyrosinase is primarily responsible for the genetic mechanism that controls human skin color. Genetics determines constitutive skin color, which is reinforced by facultative melanogenesis and tanning reactions.
Therefore dark skin is a dominant character. The lightest skin color indicates the presence of recessive alleles (aabbcc). Because melanin is a dominant phenotype, and all-white skin genes are recessive.
IT is not uncommon for two dark skinned persons to have a light skinned baby. Skin colour is a physical characteristic that is determined by genes inherited from one’s parents.
A more recent study in the same journal employed a larger set of photos than were used by either Christenfeld and Hill or Brédart and French in their studies and still concluded that most infants resemble both parents equally.
Many people believe that siblings' ethnicities are identical because they share parents, but full siblings share only about half of their DNA with one another. Because of this, siblings' ethnicities can vary.
DNA. Everyone knows that DNA is what determines your baby's appearance. But DNA is a very complex subject. Everything from hair color, eye color, height, and weight to the placement of dimples or freckles can be dictated by you or your partner's (or both!)
Your baby's skin color will change during the first few months of life, and is typically fully developed around 6 months.
The pigment, melanin, passed on to your baby by you, determines skin tone. In the same way she inherits your hair colour, the amount and type of melanin passed on to your baby is determined by a number of genes (approximately six), with one copy of each inherited from her father and one from her mother.
These variants arose about a half-million years ago, suggesting that human ancestors before that time may have had moderately dark skin, rather than the deep black hue created today by these mutations. These same two variants are found in Melanesians, Australian Aborigines, and some Indians.
Because of recombination, siblings only share about 50 percent of the same DNA, on average, Dennis says. So while biological siblings have the same family tree, their genetic code might be different in at least one of the areas looked at in a given test. That's true even for fraternal twins.
There are a few reasons why you could look different from your siblings, even if you have the same set of parents. The first reason has to do with genetics. The second reason had to do with the environment. The reason why siblings look alike is actually the same reason why they may not look alike.
It's not uncommon for children to live with siblings who share just one biological parent. In fact, one in six children under 18 live with a half sibling, according to U.S. Census Bureau estimates.
DNA is passed down randomly
Inheriting half of a parent's DNA doesn't mean inheriting half of each ethnicity. The DNA you inherit is random. One or both parents may have ethnicities that they didn't end up passing down to you–or they may have passed down only a small portion of a region they have.
After all, they both inherited half their DNA from each of the two parents. However, because of how DNA is passed on, siblings (not twins) with exactly the same ancestors can have different ethnicity breakdown. Culturally, they can say they are “1/8th Irish”, but at the DNA level, one may have no Irish genes at all.
Because boys have the sex chromosomes XY, they must inherit their Y chromosome from their father. This means they inherit all the genes on this chromosome, including things like sperm production and other exclusively male traits.
The Science Behind Daddies & Daughters
According to scientists, there is indeed evidence to suggest that firstborn daughters tend to resemble their fathers.
According to an old notion, first-born children are genetically predisposed to appear more like their father. It was thought that this was done so that the father would accept the child as his and provide for and care for them.
An article in Scientific American explains how the entire theory of newborns looking like their dad due to evolution and fathers recognizing their offspring at birth and during caveman days isn't true – according to current studies.
Pale skin in children and teenagers is rarely anything to worry about. Light-skinned children can look pale in winter because they're not getting enough sun or they're feeling cold. In rare cases, pale skin can be a sign of anaemia, infections, breathing issues and other underlying medical conditions.
It turns out that brown hair is dominant. That means that even if only one of your two alleles is for brown hair, your hair will be brown. The blond allele is recessive, and gets covered up. If two brunette parents have a blond child, they had to have instructions for making blond hair hidden in their DNA.
Multiracial babies can get much, much darker after they're born. Their hair texture can completely change, too.