Leaflet map preventing browser scroll

Whenever the mouse pointer is hovering over a leaflet map, the browser does not scroll up or down. This happens even when I affix minZoom and maxZoom to an equal value. Is there a solution to this?

php.poverty.map.2009 <-
leaflet(options = leafletOptions(minZoom = 12, maxZoom = 12)) %>%
addProviderTiles("CartoDB.Positron") %>%
addPolygons(data = php.df.polygon.2009, 
          fillColor = ~php.pal.2009(percent), 
          color = "#b2aeae", # must use hex colors
          fillOpacity = 0.7, 
          weight = 0.3, 
          smoothFactor = 0.2,
          popup = php.popup.2009) %>%
addLegend(pal = php.pal.2009, 
        values = php.df.polygon.2009$percent, 
        position = "bottomright", 
        title = "Percent of Households <br> Living below Poverty <br> (Census, 2009)",
        labFormat = labelFormat(suffix = "%"))
php.poverty.map.2009