The XX / XY preconception programme
Try with intention.
A considered 90-day programme inspired by the Shettles theory.
I'm hoping for
Supplements · nutrition · vaginal pH tests · cycle timing · companion app



Why Genesyx · The idea in 20 seconds
Shettles is the theory. Genesyx is how you follow it.
The theory proposes that vaginal environment and intercourse timing may favour X- or Y-bearing sperm. Genesyx coordinates the moving parts in one programme.
01 / Prepare
Diet + formula
XX- or XY-specific preparation.
02 / Check
Vaginal pH
At-home readings instead of guesswork.
03 / Align
Cycle + timing
Signals brought together in the companion app.
Evidence for the Shettles theory is mixed. Genesyx helps you follow the theory consistently; no outcome is guaranteed.
Your 90-day programme
Everything required for one clear route.

- 01
Formula
Three monthly packs
- 02
Nutrition
Route-specific programme
- 03
Measure
pH + cycle tests
- 04
Companion app
pH · cycle · timing
The companion app
Everything in one calm view.
Follow your selected programme with your formula, nutrition, vaginal pH and cycle timing together.
- 01Vaginal pH4.4Latest reading
- 02Cycle timingDay 12Current cycle day
- 03NutritionWeek 4Your selected guide
- 04FormulaMonth 1Your XX programme
Illustrative readings. App preview, subject to change.

A private hope
A plan you can follow together.
One shared programme, one calm app, and no guesswork about what comes next.
01What is the Shettles theory?
The Shettles theory, developed by Dr Landrum B. Shettles in the 1960s, proposes that X-bearing and Y-bearing sperm behave differently, and that the timing of intercourse around ovulation and the vaginal environment may therefore favour one over the other. It suggests intercourse two to four days before ovulation for a girl, and as close to ovulation as possible for a boy. Later research has not consistently supported the theory, so it should be treated as a method you can follow, not a proven outcome.
Read more02Why does Genesyx include vaginal pH checks?
Vaginal pH is one of the two variables the Shettles theory focuses on, so Genesyx includes at-home test strips to replace guesswork with a reading. A healthy vaginal pH is typically between 3.8 and 4.5. Genesyx never recommends douching or altering your pH with home remedies, which can cause irritation and infection.
Read more03Can Genesyx guarantee a girl or boy?
No. No natural method, including Genesyx, can guarantee the sex of a baby. Genesyx helps you follow the Shettles approach consistently, with nutrition, testing and timing in one place, but the scientific evidence is mixed and every outcome is welcome.
Read moreTry with intention
Which path are you hoping for?
Join the first-release list for your route. We'll email you once, when your programme is ready.