When it come to evolution, Darwinism (The theory of natural selection) receives greater scientific recognition than Lamarckism. Lamarckism, the theory of inheritance of acquired characteristics was proposed by Jean-Baptiste Lamarck. (1774-1829)

People often over simplify this as Giraffe neck extension theory. Lamarck believed that the traits which are acquired during a lifetime of an organism could be passed down to its offspring. For instance,one would expect a bodybuilder’s child to be born muscular. This sounds bizarre and unconvincing since traits are determined by genes.
To learn more on this matter we should look at something called “epigenetics”.
The word “epi” means “above”, so epigenetics simply means above genetics. It’s the study of the changes in organisms caused by modification of gene expression.

Let’s say you have cloned yourself. You and your clone would have the same genome and will look identical. But let’s say your clone leaves you and lives in Alaska as an eskimo for 20 years. After that time when you meet again you may look a bit different but your genome will still be the same. That is to say if your genome is a paragraph, all of the letters will be the same. But the punctuation and the spacing of the words will be different. Therefore the message which it conveys will be different. This genetic punctuation is “epigenetics”.

All of our cells contain the same genes but not all of them are expressed in every cell. This is why the heart muscle cell differs from an eyeball cell. Epigenome controls whether the genes should be expressed or not. Epigenetics suggests that the genes expression can be altered, not randomly as in darwinism by specific predictable manner like Lamarck suggested.

Two main systems involved in epigenetics are methylation and histone modification. Methylation is how methyl groups bind to the gene and controls it like a switch. These methyl groups bind differently on each cell so not all genes are expressed. DNA methylation takes place during embryonic development, x-chromosome inactivation, etc. Histones act differently, they control how tightly or loosely the DNA is wound around. So histones act as a knob and control how genes are expressed.

Every cell in your body has a distinct methylation and histone pattern. Genome acts like the hardware and epigenome acts more like the software telling the hardware what to do. Environmental factors and behavioural factors change the way methyl groups bind to our genes. Although the hardware genome remains the same throughout your life epigenome changes.

Are these epigenetic tags hereditary?

You can consume a large pizza a day and think this would affect your unborn child. Darwin suggests not! Even though lots of those epigenetics tags are removed some may be passed onto the new generation.

So in conclusion environmental factors can change your epigenome and also these changes can be passed onto the next generation. So basically this suggests that the reason to your health issues may be due to the diet of your grandmother.

Lamarck was right all along and deserves more credit for his theory.
Your decisions today will affect generations after you. Just think about it!!!

References: http://evolutionnews.org/2015/08/epigenetic_chan/

Image credits: www.google.lk