Can DNA differ from one sibling to another? The experts say “YES”. From an article posted by Anna Swayne on March 5, 2014 on Ancestry.com titled, “Understanding Patterns of Inheritance: Where Did My DNA Come From? (And Why It Matters.)” we read:
The chart helps illustrate how different segments of DNA might have been passed down from your grandparents to make your unique DNA. Assume each letter represents a segment of DNA. Things to notice are: Which letters get passed down to each generation is random (the fact that the letters spell names in this example is simply to help with the illustration).
Not all of the letters get passed down.
Just because a child doesn’t have a letter doesn’t mean that an earlier ancestor didn’t have that letter.
Siblings can have different combinations of letters.
To see a visual chart of this please go to the article published by Ancestry.com.
This article helps to understand how different characteristics are manifest amongst brothers and sisters within the same family.
My Kindred Tree 