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What You'll Get
- ✓ A probability nudge based on maternal genetic variants
- ✓ Your genotypes at exploratory loci (NSUN6, TSHZ1)
- ✓ Plain-English explanation with uncertainty bands
- ✓ Context from Harvard's 2025 large-scale study
- ✓ Fun facts about family sex ratio patterns
"Interesting, not instructive: treat this as a fun, data-driven curiosity with tiny effects."
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What We Test
Based on a 2025 Harvard study of 58,000+ mothers showing maternal genetic variants weakly associated with having children of predominantly one sex. Effects are subtle and probabilistic.
| Variant (rsID) | Gene Region | Association | Effect Size |
|---|---|---|---|
| rs58090855 Science | Near NSUN6 | Female-only families | +2-3% tilt |
| rs1506275 PMC | Near TSHZ1 | Male-only families | +2-3% tilt |
| Additional exploratory markers from CYP2U1 and other regions may be included | |||
🎯 Fun Fact from the Study
In families with 3 boys, the probability of a 4th boy was ~61% (vs 51.9% baseline). In families with 3 girls, the probability of a 4th girl was ~58%. Small but measurable!
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The Science Behind It
The Harvard Study (2025)
Researchers analyzed 146,000+ births and found that sex distributions within families deviate slightly from random chance. Some families show subtle, heritable tilts toward one sex. The study identified maternal genetic variants that correlate with these patterns, though effects are tiny. Science Advances Harvard News
What These Genes Might Do
NSUN6 encodes a tRNA methyltransferase affecting RNA stability. TSHZ1 is a transcription factor in neural development. These could theoretically influence early embryo viability or implantation in sex-specific ways, but mechanisms remain speculative. The biology is fascinating but unproven! PMC
Other Factors Matter More
Maternal age at first birth shows stronger associations than genetics. Environmental factors, timing, and pure chance dominate offspring sex determination. These genetic variants explain less than 1% of variation—detectable at population scale but nearly meaningless for individuals.
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How We Test
Saliva Collection
Simple at-home kit
DNA Extraction
CLIA-certified lab
PCR Analysis
Target variants
Fun Report
5-7 business days
We combine your genetic results with self-reported factors like maternal age to generate a gentle probability nudge. Remember: this is for entertainment and curiosity!
⚠️ Critical Ethics & Limitations
- NOT for sex selection or reproductive decisions
- NOT suitable for IVF/embryo selection guidance
- NOT medical advice in any form
- Effects are TINY (2-4% at most) and highly uncertain
- Each individual pregnancy remains essentially 50/50
- Many other factors matter more than these variants
- Results should not influence family planning decisions
This is curiosity science only. Please treat it as such.
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Interesting Context
Historical Perspective
For over a century, we believed sex determination was purely about whether sperm carries X or Y. This research suggests maternal biology might subtly influence the odds—a tiny wrinkle in the textbook story. It's scientifically intriguing even if practically irrelevant!
Global Patterns
Some families really do have all boys or all girls more often than chance predicts. While most is random variation, this study suggests a small biological component exists. Evolution may have preserved these variants for reasons we don't understand.
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Your Privacy
You own your genetic data. Export it anytime as raw data files. Delete it with one click. We never share your information without explicit consent. Learn more about our privacy practices →