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Number of hours spent outdoors daily during summer between the ages of 13 and 19 comparing twins discordant for melanoma.
| Unaffected | |||||
|---|---|---|---|---|---|
| None | Up to 1 hour | 1–3 hours | More than 3 hrs | ||
| Affected | None | 0 | 0 | 1 | 0 |
| Up to 1 hour | 1 | 6 | 11 | 6 | |
| 1–3 hours | 0 | 5 | 14 | 10 | |
| More than 3 hrs | 0 | 4 | 1 | 8 | |
