Family Tree

What is a family tree? How can you recognise your gifts and who are they helpful to?

“Rohit has a good sense of humour. Kiara loves lady fingers but hates capsicums. New boy who joined our class today can roll his tongue”. Prisha was on the top of her excitement while explaining to her mother about the Biology lesson she took today in the school. She continued as her excitement knew no boundaries that all these characteristics from how funny someone can be to whether he likes ladyfingers or capsicums or whether he can roll his tongue depend upon the complex gene pool that we inherited from her parents.

 

Genes which are the part of our DNA pass from parents to offsprings by the process called inheritance and all the characteristics we possess whether physical or behavioural are governed by the genes. That is why members of a family have similar characteristics or traits. If we trace a particular trait over generations through a genetic line, a family tree can be framed for that characteristic. The moment any child is born in a family relatives look for reflections of themselves in him. Parents’ traits can go beyond eye colour and hair textures. Genes can even shape personality traits like leadership, decision making and problem solving quality.

 

Prisha’s brown eyes are not surprising to her mother as she herself has brown eyes and brown eye colour is a dominant trait over any other eye colour. This can be understood in a simple way. We have two alleles of a gene for each trait of ours. One allele is contributed by each parent. The allele which is dominant gets expressed in the offspring and the other allele which is not expressed is called recessive allele. So if any one parent has brown eyes allele the child will get brown eyes regardless of the eye colour of the other parent because the dominant gene of brown colour will win over recessive blue colour or any other colour allele.

 

A particular heritable trait can be studied over generations in a family line and can be represented in the form of a tree which is called a family tree for that trait. Look at the tree below where females are represented with circles and males with squares. Horizontal lines represent the members of same generation; parents and siblings. Vertical lines show next generation with siblings attached to them horizontally. The circles or squares which are shown in blue (solid) indicate the trait under consideration.

Suppose father has brown eyes in first generation and he has dominant allele for brown eyes, the dominant allele is passed on to one of his boys and one girl in next generation and they got their eye colour brown and same goes on over the genetic line.

 

Kindly note genes are only one influence on our traits. How kids will turn out in their physical traits can depend upon genes on larger extent but personality traits depend upon amalgamation of inherited genes and their interaction with environment. Understanding of how genes and environment interact with each other is not perfectly known. Genes are just one influence of how kids will develop into. 

Identical twins have exact same gene pool or DNA which is why they look exactly alike.

Dear readers, I recommend you to draw a family tree of your family taking example of a physical trait. It is going to be fun. Select a physical trait, talk to your parents about the presence or absence of that trait in them. Discuss with your uncles and aunts; your grandparents, both paternal and maternal. Ask them about their siblings and your great grandparents and complete you family tree.

 You can do this activity of making family tree to see how some characteristics in your family can help you determine the inheritance pattern in your family. You will discover some characteristics that you have inherited from your dad side (paternal) of the family and for this you can thank him on Father’s day for gifting those characteristics to you. Same goes for your mother on Mother’s Day. 

But as I mentioned earlier this is not applicable to all the traits which we have. Along with our gene pool, there are other factors like environment, nutrition and gene mutations which play their role and govern our physical, cognitive and behavioural characteristics. 

So do not trick your mother saying you will not eat capsicums because father has not given you that allele of a gene which makes you like capsicums because it can happen so; the capsicum liking allele which is recessive in your father can be dominant in you.

 

 

                                                                                                       Iqbal Kaur Rana

                                                                                                                   Principal