About TwinCalc
An informational statistical tool based on published research — not a clinical service.
An informational, research-based statistical tool.
TwinCalc is an informational, research-based statistical tool. Model v2.0 separates a stable identical-twin component from a fraternal-twin component adjusted with conservative heuristic weights. It is not clinically validated; treatment-specific risk is deliberately excluded and every modelling choice is documented.
Read the full model on our methodology page. TwinCalc is free, contains no advertising, and sells nothing.
Where the line is, plainly.
We want to be precise about our scope. TwinCalc is:
- • Not medical advice. The calculator cannot diagnose, predict, or replace a clinical consultation.
- • Not personally reviewed by any physician. No named doctor or clinician has examined or validated the content. Editorial decisions are made using public, peer-reviewed sources.
- • Not a substitute for a professional consultation. Talk to a qualified healthcare provider for guidance on your situation.
- • Not controlled by any clinic, hospital, health authority, pharmaceutical brand or commercial partner. Paid products and affiliate relationships, if introduced, are labelled and never influence the calculator or editorial conclusions.
Public datasets and peer-reviewed journals.
The model and articles draw on public datasets and guidelines from the National Institutes of Health (NIH National Vital Statistics), the American Society for Reproductive Medicine (ASRM), the American College of Obstetricians and Gynecologists (ACOG), and the World Health Organization (WHO), plus indexed journals (Human Reproduction, Twin Research and Human Genetics, Obstetrics & Gynecology, Reproductive Sciences).
Every multiplier and assumption is documented on the methodology page, with the underlying study referenced.
How we write.
- • Cite every factual claim. Each heuristic weight, exclusion and limitation links to the evidence review.
- • Be explicit about uncertainty. Where evidence is mixed, we say so.
- • Stay informational. We do not give individualized medical advice.
- • Update transparently. Every page carries a last-updated date and corrections are acknowledged on the page.
Editorial principles
How we write — and what this tool is not.
Primary and peer-reviewed sources
Pages link directly to CDC, ASRM, HFEA, HMBD and the peer-reviewed studies actually used.
Transparent methodology
Heuristic weights, exclusions, formula and guardrail are documented and dated.
No claimed clinical validation
Educational tool not reviewed by a named physician. It does not predict an individual outcome or replace a clinician.
Contact
Questions, corrections, or methodology feedback are welcome. We read every email.