Checkbox {% include 'elements/forms/checkbox' %}
#
HTML 
<div class="field-set">
    <div class="field-set__content">
        <div class="field-set__items">
                            <div class="field-set__item">
                    <input class="field-set__input field-set__input--checkbox default-style" id="checkbox1" name="checkbox" type="checkbox" />
                    <label class="field-set__label field-set__label--checkbox" for="checkbox1"><span class="field-set__label-text">This is a really long choice that could be used as a confirmation</span></label>
                </div>
                            <div class="field-set__item">
                    <input class="field-set__input field-set__input--checkbox default-style" id="checkbox2" name="checkbox" type="checkbox" />
                    <label class="field-set__label field-set__label--checkbox" for="checkbox2"><span class="field-set__label-text">Choice B</span></label>
                </div>
                            <div class="field-set__item">
                    <input class="field-set__input field-set__input--checkbox default-style" id="checkbox3" name="checkbox" type="checkbox" />
                    <label class="field-set__label field-set__label--checkbox" for="checkbox3"><span class="field-set__label-text">Choice C</span></label>
                </div>
                    </div>
    </div>
</div>
Twig 
<div class="field-set">
    <div class="field-set__content">
        <div class="field-set__items">
            {% for value in values %}
                <div class="field-set__item">
                    <input class="field-set__input field-set__input--checkbox default-style" id="checkbox{{loop.index}}" name="checkbox" type="checkbox" />
                    <label class="field-set__label field-set__label--checkbox" for="checkbox{{loop.index}}"><span class="field-set__label-text">{{value}}</span></label>
                </div>
            {% endfor %}
        </div>
    </div>
</div>

{
    "label": "Title",
    "values": {
        "1": "This is a really long choice that could be used as a confirmation",
        "2": "Choice B",
        "3": "Choice C"
    }
}