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Thank you for being part of Gemini for the last 11-12 years. Please find the links for the online parent questionnaire and game below. If possible, try to complete the whole questionnaire (35 to 40 minutes) and the online game (10 minutes) in a single session. Please complete the questionnaire on a laptop, a desktop or a tablet. Please do not do the online game on a mobile phone or a tablet.

Body measurements

In the questionnaire we will ask you to measure your and your twins'waist circumferences using the tape measure and instructions we sent you by post. You will also need to have measured the twins’ heights and weights and to have made a note of all the measurements before completing the questionnaire so you can enter them when prompted. Watch the short instruction video on the right which shows you how to measure waist circumference correctly.


  • Don't use your browser's navigation buttons (e.g., Back or Refresh) during the study, as this could cause some of your progress to be lost.

  • Once you press 'submit' or 'save and return' you can't go back and change your answers

  • If you need to take a break, or your session is interrupted, you can log in again later by clicking save and return and making a note of the return code.

  • If you have any technical problems, try closing your browser and logging in again, or using a different browser. 

Online game

  • Thank you for your interest in the online game. Unfortunately, the online game is no longer available as we have finished data collection for this part of the study.

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