Genetics has a great deal to say about the timing of reproduction across populations and almost nothing to say to one person trying to conceive.
Why this topic Birth rates are a headline in a dozen countries at once, egg freezing has become ordinary, and IVF is discussed in the open by people who would not have mentioned it a decade ago.
Solid lines are connections this site curates. Dashed lines mean the two ends share a research paper — worth knowing, and not a claim that one explains the other.
Counted in Europe PMC, where the title or abstract names both this topic and that rsID. The number is papers, not evidence of a cause.
MTHFR
Folate metabolism (MTHFR C677T)
11 papers →KITLG
Testicular germ cell tumor
6 papers →MTHFR
Folate metabolism (MTHFR A1298C)
5 papers →near MRPS30
Breast cancer
3 papers →ZFP36L2
Polycystic ovary syndrome
3 papers →MCM8
Menopause (age at onset)
3 papers →HLA-DQA2
Crohn's disease
3 papers →LSP1
Breast cancer
3 papers →STAT4
Systemic lupus erythematosus
2 papers →ZFP36L2
Polycystic ovary syndrome
2 papers →GREB1
Endometriosis
2 papers →CDKN2B-ASI
Endometriosis
2 papers →SYCP2L
Menopause (age at onset)
2 papers →SLCO1B1
Statin muscle-side-effect risk
2 papers →SLC4A7
Breast cancer
2 papers →COX11
Breast cancer
2 papers →STAT4
Type 1 diabetes
2 papers →TERT
Breast cancer
1 paper →TAS2R38
Bitter taste perception (TAS2R38 position 296)
1 paper →PRRC2A
Menopause (age at onset)
1 paper →DENND1A
Polycystic ovary syndrome
1 paper →SCARB1
Lipoprotein-associated phospholipase A2 activity and mass
1 paper →ZNF365
Breast cancer
1 paper →IL23R
Crohn's disease
1 paper →LDLR
Myocardial infarction (early onset)
1 paper →BRCA2
Cancer
1 paper →BRSK1
Menarche and menopause (age at onset)
1 paper →SHBG
Testosterone levels
1 paper →ADH1B
Alcohol metabolism speed
1 paper →MC4R
Waist circumference and related phenotypes
1 paper →FTO
Obesity
1 paper →SLC2A9
Urate levels
1 paper →ICAM1
Soluble ICAM-1
1 paper →TGFB1
Colorectal cancer
1 paper →BCHE
Cardiovascular disease risk factors
1 paper →ESR1
Breast cancer
1 paper →FTH1
Plasma omega-6 polyunsaturated fatty acid levels (linoleic acid)
1 paper →TERT
Lung adenocarcinoma
1 paper →CCR5
HIV-1 resistance (CCR5-delta32)
1 paper →TYK2
Type 1 diabetes
1 paper →CYP2C19
CYP2C19 *2 — clopidogrel activation
1 paper →ACE
Angiotensin-converting enzyme activity
1 paper →SPRY4
Testicular germ cell tumor
1 paper →ICAM1
Soluble ICAM-1
1 paper →F5
Blood clotting risk (Factor V Leiden)
1 paper →ALDH2
Alcohol flush reaction
1 paper →ITPA
Chronic hepatitis C infection
1 paper →GCKR
Crohn's disease
1 paper →FTO
Type 2 diabetes
1 paper →Europe PMC, title and abstract only, searched for “age at first birth”, “infertility”, “ovarian reserve” alongside each published rsID. Full text was not counted: it returns every paper with an rsID buried in a supplementary table. Recounted monthly.