Genes are composed of a sequence of nucleotides that code for a functional protein, straddled between a start and stop codon and are regulated by a promoter and regulator upstream. DNA, on the other hand, is a sequence of deoxyribonucleotides in an antiparallel double-helix chain. Genes are contained in the DNA double helix. Chromosomes are long DNA strands that are we packaged to into the small of the nucleus in a cell. The chromosomes contain packaging proteins such as histones in which DNA is wound to form nucleosomes.
This is because a population has different alleles (varying forms) of a gene distributed across the population in different frequencies. These alleles are passed down generation by parents to offspring. Each parent gives one allele to its offspring in diploid organisms. The difference in traits is because of this variation in the genotype of an organism. Additionally, how this genotype interacts with the environment to give the individual his phenotypic trait also give individuals varying traits.
An example of such a trait is my wavy hair, an observable trait I have because one of my parents has straight hair while the other has curly hair. I inherited an allele from both parents for hair texture. Since both allele exhibit incomplete dominance, I, therefore, have wavy hair.
