Genetics: Why you may inheret a disease?

Question

Genetics: Why you may inheret a disease?

Is it possible that people who have a 'genetic' disposition, a vulnerability to a disease, may in fact have a vulnerability to certain bacteria, certain viruses, or certain parasites ?

I guess what I am trying to get at is that genetics is only part of the problem...the real problem is the virus that attacks the system, much like a computer virus, will attack a computer that has a 'weakness' and all similar computers that have the same weakness...

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Answer 1

genetic scientists use something called a punnett square to show the probablility of offspring inheriting a gene, i will try my best to explain this to you, as i am only in ninth grade, but we just had a test on this.

if the disease is dominant:

*if one parent has it, the offspring will have either a 100% or 50% chance of having it, depending on the genotype of the parent.
*a physical trait is determined by a genotype, which is a scientific way of writing the alleles of a gene.
*an allele is a variation of a gene.
*i am going to use an example of an unspecific disease and the alleles will be represented by the letter D,
so DD = homozygous dominant, Dd = heterozygous, and dd= homosygous recessive
(hymozygous- two same alleles; heterozygous-two different alleles)

*if a parent carries two dominant alleles, not matter what allele they give to the offspring, the child will have the disease.
this is because the dominant allele will power over the recessive allele.
if a parent is heterozygous, then it depends if they give the dominant or recessive gene so there is a 50% chance of the offspring having the disease, regardless of what the other parent gives.
*if a parent has two recessive alleles, they do not have the disease and cannot pass it on to their offspring, however if they reproduce with someone who does have the disease there is a 100% chance if they are homozygous dominant and 50% if they are heterozygous. if the other parent is homozygous recessive, then there is no chance of the child to get this disease.

if the disease is recessive:

both parents must be either heterozygous or homozygous recessive for the child to have the disease, if one parent is homozygous dominant, there is no chance of the child getting the disease. This is because for the disease to be present, there must be two recessive alleles present in the offspring.