Question

What is the mode of inheritance?

Answer 1

Inheritance is a process by which genetic information is passed from a parent to the offspring. Hence, members of the same family possess the same characteristics. It happens either via asexual reproduction or sexual reproduction. Genetics is a branch, which deals with the study of heredity.
It is the transmission of traits, information and genomic sequences to the children.

Complete answer
Mode of inheritance is a manner by which a genetic trait or a genetic disorder is passed on from one generation to subsequent generations.
There are basically five modes of inheritance. They are as follows:
1. Autosomal recessive
2. Autosomal dominant
3. X-linked recessive
4. X-linked dominant
5. Mitochondrial

1. Autosomal dominant: It indicates genetic conditions, which occur when a mutation is present in a single copy of a given gene (provided the person is heterozygous).
Example for autosomal dominant genetic disorder is hereditary breast cancer syndrome, which is related with pathogenic variants BRCA$1$, BRCA$2$ and PALB$2$

2. Autosomal recessive: It takes place only when the mutation is present in both copies of a given gene. Here, the person is homozygous for the mutation. Examples are cystic fibrosis and sickle cell anemia.

3. X-linked dominant: It hints at genetic conditions, which are associated with mutations in the X chromosome only. A single copy of mutation is sufficient to cause disease in females (two X chromosomes) and male (one X chromosomes). During some situations, absence of a functional gene can cause death in male.

4. X-linked recessive: It is also associated with mutations in the X chromosome. A female, who carries a mutation in a gene, possessing a normal gene in another X chromosome is usually unaffected. But the male carrying a mutation is affected as he carries only one X chromosome

5. Mitochondrial: Mitochondria possess their own genetic material apart from the genetic material present in the nucleus. Mitochondria and mitochondrial DNA are passed from mother to children.

Note:
First degree relatives include siblings, parents and offspring. They share $50\%$ of DNA. Second degree relatives include uncles, aunts, grandchildren, grandparents, nephews, nieces and half siblings. They share $25\%$ of DNA. Third degree relatives include first cousins. They share $12.5\%$ of DNA. Pedigree is a term for the graphic illustration of family history, where relationships between family members are displayed.