title: dplyr filter with condition on multiple columns
body: <p>I'd like to remove rows corresponding to a particular combination of variables from my data frame.</p>
  <p>Here's a dummy data :</p>
  <pre><code>father&lt;- c(1, 1, 1, 1, 1)
  mother&lt;- c(1, 1, 1, NA, NA) 
  children &lt;- c(NA, NA, 2, 5, 2) 
  cousins   &lt;- c(NA, 5, 1, 1, 4) 
  
  
  dataset &lt;- data.frame(father, mother, children, cousins)  
  dataset
  
  
  father  mother  children cousins
  1      1       NA      NA
  1      1       NA       5
  1      1        2       1
  1     NA        5       1
  1     NA        2       4
  </code></pre>
  <p>I want to filter this row :</p>
  <pre><code>  father  mother  children cousins
      1      1       NA      NA
  </code></pre>
  <p>I can do it with :</p>
  <pre><code>test &lt;- dataset %&gt;% 
  filter(father==1 &amp; mother==1) %&gt;%
  filter (is.na(children)) %&gt;%
  filter (is.na(cousins))
  test  
  </code></pre>
  <p>My question :
  I have many columns like grand father, uncle1, uncle2, uncle3 and I want to avoid something like that:</p>
  <pre><code>  filter (is.na(children)) %&gt;%
    filter (is.na(cousins)) %&gt;%
    filter (is.na(uncle1)) %&gt;%
    filter (is.na(uncle2)) %&gt;%
    filter (is.na(uncle3)) 
    and so on...
  </code></pre>
  <p>How can I use dplyr to say filter all the column with na (except  father==1 &amp; mother==1)</p>