Final answer:
An individual inherits approximately 25% of their genes from each grandparent. Environmental factors and personal experiences further contribute to variations from parents. Nuclear DNA is inherited evenly from both parents, while mitochondrial DNA is solely from the mother.
Step-by-step explanation:
Every individual inherits 50% of their genes from each parent. Consequently, the genes you get from your mother will include half of her genetic material, of which 50% is derived from her father (your maternal grandfather) and 50% is derived from her mother (your maternal grandmother).
The same pattern applies to your father's contribution to your genes - half from your paternal grandfather and half from your maternal grandmother. Therefore, you inherit about 25% of your genes from each grandparent.
Personal experiences and the environment play significant roles in making you different from your parents despite the genetic similarities. These factors contribute to the unique expression of your genes, resulting in individual variations in appearance, personality, and other traits.
Moreover, it's important to distinguish between nuclear DNA, which follows the 50% inheritance from each parent, and mitochondrial DNA (mtDNA), which is inherited exclusively from the mother.