wie viele gene hat ein mensch — what does this mean exactly?

The question 'how many genes does a human have' is more complex than it seems. The initial estimate from the Human Genome Project was around 20,000–25,000 protein-coding genes. However, this number is an approximation because the definition of a gene is evolving: besides classical protein-coding sequences, there are numerous non-coding RNA genes, pseudogenes, and regulatory elements. Current reference databases like GENCODE list about 19,000–20,000 protein-coding genes, but the total count of all functional gene units (including lncRNAs, miRNAs, etc.) is much higher. For practical purposes, this means that a DNA test focusing only on protein-coding genes captures only a fraction of the genome. The relevance for health and nutrition is limited because most polygenic traits are influenced by many small effects spread across the entire genome. Knowing the exact gene count is scientifically interesting but less important for personal health decisions than the functional interpretation of specific variants.