如何针对三个时间点中的每一个绘制一个变量

I have a dataset containing one DV called Soma(Somatotype) and three IV called WT2(weight at age 2),WT9(weight at age9),WT18(weight at age18) and I am going to plot Soma against weight at each of the three time points. But since it is not exactly like a time series dataset and I am totally stuck with this. I was thinking of use ggplot but I am not familiar with that and failed a lot. The dataset:I have a dataset containing one DV called Soma(