Marc Thompson said the "hardest thing is not knowing" where his twin brother Ben is.
The 34-year-old from Haverfordwest has been missing since Saturday, after he watched Wales' Six Nations game at the Millennium Stadium.
He told our Correspondent Carole Green that this would be "very out of character" for him not to contact his family.
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After a dry end to the day, there'll be a few showers this evening Winds getting stronger overnight.
If you missed tonight's episode of Wales This Week, Test Tube Triumph, you can now catch up here
Jean Davies said her life had become "intolerable". Her daughter Bronwen speaks to ITV News about the decision.