Obesity is the disease that significantly affects human life as a combination of genetic and physiological environment. The polygenic background of the disease causes of childhood or adulthood obesity are still not fully understood. Childhood obesity and adulthood obesity are usually expressed in terms of body fat mass and body mass index (BMI). Obesity is a comorbid disease that is often associated with T2D, cardiovascular diseases, fatty liver and various mental health problems. Therefore, examining the genetic background of the disease is also important for epidemiological studies. Obesity, which is one of the multi-gene diseases, is revealed by genome-wide research studies, candidate gene studies by SNP genotyping assays. SNP genotyping analyzes not only provide information about the transmission of childhood obesity, but also provide significant guidance on the biological pathways of the disease. Genome-wide association studies (GWAS) provide effective research in association studies between anthropometric body characteristics and the genome. The aim of this thesis is to investigate childhood related obesity variants, adulthood related obesity variants, to identify relationship of these two groups of genetic variants. In addition, the purpose of the thesis, is to understand effects of the variants on metabolic pathways, the difference of childhood and adulthood obesity related pathways and calculation of polygenic risk.