Traits are passed down through generations via the following process:

1. Genes: Segments of DNA that code for specific traits
2. Alleles: Different versions of a gene
3. Inheritance: Each parent contributes one allele for each gene to their offspring
4. Dominant and recessive traits: Some alleles are dominant (always expressed), others are recessive (only expressed when two copies are present)
5. Punnett squares: Used to predict the probability of offspring inheriting specific traits
6. Mutations: Random changes in DNA that can create new alleles and traits

Genetic inheritance patterns:

1. Autosomal dominant: One copy of the allele is sufficient to express the trait
2. Autosomal recessive: Two copies of the recessive allele are needed to express the trait
3. X-linked dominant: Trait is on the X chromosome and one copy is sufficient for expression
4. X-linked recessive: Trait is on the X chromosome and affects males more frequently
5. Codominance: Both alleles are expressed equally in the phenotype
6. Incomplete dominance: Neither allele is completely dominant, resulting in a blended phenotype

Epigenetics and gene expression:

1. Definition: Changes in gene expression without altering the DNA sequence
2. DNA methylation: Addition of methyl groups to DNA can silence genes
3. Histone modification: Changes to histone proteins affect DNA packaging and gene accessibility
4. Environmental factors: Diet, stress, and toxins can influence epigenetic changes
5. Heritability: Some epigenetic modifications can be passed to offspring
6. Reversibility: Unlike genetic mutations, epigenetic changes can potentially be reversed