nested ifelse in R so close to working

I'm working with the following four columns of raw weight measurement data and a very nearly-functioning nested ifelse statement that results in the 'kg' vector.

     Id       G4_R_2_4         G4_R_2_5        G4_R_2_5_option2          kg
219 13237       16.0             NA                  NA                16.0
220 139129      8.50             55.70               47.20             8.50
221 139215      28.9             NA                  NA                28.9
222 139216       NA              46.70               8.50              46.70
223 139264      12.40            NA                  NA                12.40
224 139281      13.60            NA                  NA                13.60
225 139366      16.10            NA                  NA                16.10
226 139376      61.80            NA                  NA                61.80
227 140103      NA               48.60               9.10              48.60

The goal is to merge the three 'G4' columns into kg based on the following conditions: 1) If G4_R_2_4 is not NA, print its value 2) If G4_R_2_4 is NA, print the lesser of the values appearing in G4_R_2_5 and G4_R_2_5_option2 (sorry for lame variable names)

I've been working with the following statement (big dataset called 'child'):

> child$kg <- ifelse(child$G4_R_2_4 == 'NA' & child$G4_R_2_5 < child$G4_R_2_5_option2,
   child$G4_R_2_5, ifelse(child$G4_R_2_4 == 'NA' & child$G4_R_2_5 > child$G4_R_2_5_option2,
                          child$G4_R_2_5_option2, child$G4_R_2_4))

Which results in the 'kg' vector I have now. It seems to satisfy the G4_R_2_4 condition (is/is not NA) but always prints the value from G4_R_2_5 for the NA cases. How do I get it to incorporate the greater than/less than condition?