The *Players Handbook* has the following optional traits for humans:

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> **Variant Human Traits**
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> If your campaign uses the optional feat rules from chapter 7, your Dungeon Master might allow these variant traits, all of which replace the human's Ability Score Increase trait.
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> ***Ability Score Increase.*** Two different ability scores of your choice increase by 1.
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> ***Skills.*** You gain proficiency in one skill of your choice.
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> ***Feat.*** You gain one feat of your choice.
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> (*Player's Handbook*, page 31)
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**Can I decide to use this variant traits after rolling my stats, or do I have to make that decision before?**

I ask because the stats that are rolled could result in big gains in total modifiers if all stats are increased, with a lot of odd numbers, but if you only get 2 or less odd numbers, increasing the other skills will not result in any increase to the total skill modifiers you end up with, and thus taking the optional traits would essentially net you a free feat and skill proficiency.

To illustrate, suppose I rolled 15, 13, 12, 11, 11, 9.  

In this example, my modifiers would be +2, +1, +1, +0, +0, and -1 (total 3).  

By taking the default trait, I would end up with 16, 14, 13, 12, 12, 10, and my modifiers would be +3, +2, +1, +1, +1, +0 with a total of 8 - a big improvement, whereas by taking the optional traits, I could only increase my modifiers 2, to 5 total. So in this circumstance I would prefer to take the overall increase.

Suppose instead I rolled 16, 14, 13, 12, 10, 10 with modifiers +3, +2, +1, +1, +0, +0.  

In this instance taking the default trait I would end up with 17, 15, 14, 13, 11, 11 and modifiers +3, +2, +2, +1, +0, +0. This only nets me an increase of 1 to my modifiers, which would be the same as taking the optional traits.  

Hence in this situation, I would want to take the optional traits because the feat and skill proficiency are essentially free.